119 lines
2.6 KiB
Go
119 lines
2.6 KiB
Go
// Copyright (C) 2019 Storj Labs, Inc.
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// See LICENSE for copying information.
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package stream
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import (
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"context"
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"io"
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"storj.io/common/storj"
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"storj.io/storj/uplink/metainfo/kvmetainfo"
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"storj.io/storj/uplink/storage/streams"
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)
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// Download implements Reader, Seeker and Closer for reading from stream.
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type Download struct {
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ctx context.Context
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stream kvmetainfo.ReadOnlyStream
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streams streams.Store
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reader io.ReadCloser
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offset int64
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limit int64
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closed bool
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}
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// NewDownload creates new stream download.
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func NewDownload(ctx context.Context, stream kvmetainfo.ReadOnlyStream, streams streams.Store) *Download {
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return &Download{
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ctx: ctx,
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stream: stream,
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streams: streams,
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limit: -1,
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}
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}
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// NewDownloadRange creates new stream range download with range from offset to offset+limit.
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func NewDownloadRange(ctx context.Context, stream kvmetainfo.ReadOnlyStream, streams streams.Store, offset, limit int64) *Download {
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return &Download{
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ctx: ctx,
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stream: stream,
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streams: streams,
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offset: offset,
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limit: limit,
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}
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}
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// Read reads up to len(data) bytes into data.
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//
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// If this is the first call it will read from the beginning of the stream.
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// Use Seek to change the current offset for the next Read call.
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//
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// See io.Reader for more details.
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func (download *Download) Read(data []byte) (n int, err error) {
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if download.closed {
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return 0, Error.New("already closed")
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}
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if download.reader == nil {
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err = download.resetReader(download.offset)
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if err != nil {
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return 0, err
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}
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}
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if download.limit == 0 {
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return 0, io.EOF
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}
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if download.limit > 0 && download.limit < int64(len(data)) {
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data = data[:download.limit]
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}
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n, err = download.reader.Read(data)
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if download.limit >= 0 {
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download.limit -= int64(n)
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}
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download.offset += int64(n)
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return n, err
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}
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// Close closes the stream and releases the underlying resources.
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func (download *Download) Close() error {
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if download.closed {
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return Error.New("already closed")
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}
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download.closed = true
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if download.reader == nil {
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return nil
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}
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return download.reader.Close()
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}
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func (download *Download) resetReader(offset int64) error {
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if download.reader != nil {
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err := download.reader.Close()
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if err != nil {
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return err
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}
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}
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obj := download.stream.Info()
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rr, err := download.streams.Get(download.ctx, storj.JoinPaths(obj.Bucket.Name, obj.Path), obj, obj.Bucket.PathCipher)
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if err != nil {
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return err
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}
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download.reader, err = rr.Range(download.ctx, offset, obj.Size-offset)
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if err != nil {
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return err
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}
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download.offset = offset
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return nil
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}
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